This study will support the indication for use of BRL 49653C as combination therapy with insulin for the reduction of hyperglycemia in the management of patients with NIDDM. The primary objective is to evaluate the effectiveness of BRL 49653C 2 mg bid and 4 mg bid in reducing hyperglycemia when administered to NIDDM patients who are inadequately controlled (i.e., FBG<140 mg/dL) on insulin alone. The primary endpoint will be the change form baseline in HbA1c after 26 weeks of treatment.